Muffler



May 2, w57 vv. H. POWERS ETAe.. 3,317,001

MUFFLER Original Filed Nov. 4 1963 May 2, 1967 vv. H. POWERS ETAL.3,317,001

MUFFLEH 2 Sheets-Sheet 2 Original Filed Nov. 4, 1963 United StatesPatent O 3,317,001 M'UFFLER Walter H. Powers and Ervin C. Lentz, Racine,Wis., and Karl K. Kcrns, Jackson, Mich., assiguors to WalkerManufacturing Company, Racine, `Wis., a corporation of DelawareContinuation of application Ser. No. 321,007, Nov. 4, 1963. Thisapplication May 16, 1966, Ser. No. 550,574 Claims. (Cl. 181-36) 'I'hisapplication is a continuation of our application Ser. Number 116,839,filed lune 13, 1961, and entitled, Muffler.

Our invention relates to the handling of exhaust gases and, inparticular, concerns a combination exhaust gas conduit and silencer thatis peculiarly well adapted for use on modern, low-slung automobiles.

It is an object of our invention to provide a combined conduit andsilencing system that is very small in diameter and relatively long inlength and adapted to readily t or be `tted in the small space allocatedfor the exhaust system in modern automobiles.

While other arrangements are possible, in a preferred form, ourinvention comprises a combined conduit and silencer unit that h'as alaminated pipe at its inlet end which receives exhaust gases from theexhaust manifold. A high pass silencing member is connected to thedownstream end of the laminated pipe. The outlet of the high pass memberis connected to a low pass member. There after the high pass and lowpass members are alternated, the unit terminating in a low pass member.

The invention is illustrated in the accompanying drawings in which:

FIGURE 1 is a somewhat diagrammatic side elevation, partly broken away,of a combined exhaust conduit and silencing system embodying theprinciples of the invention;

FIGURE 2 is a cross-section broken away along a line 2 2 of FIG. l,showing a laminated pipe;

FIGURE 3 is a cross-section along a line 3--3 of FIG. 1 showing one formof high pass member that may be used;

V FIGURE 4 is a cross-section along the line 4-4 of FIG. 1 showing oneform of low pass member that may be used;

FIGURE 5 is a section through another form of high pass silencingmember; and

FIGURE 6 is a plan view, partly in section, of an exhaust systemembodying the invention for use on a dual manifold engine, the low passor spit chamber members being out of scale.

In FIG. 1 an internal combustion engine 1 has an exhaust manifold 3which empties exhaust gases into an exhaust system 5. The system 5 isintended to replace the conventional exhaust system which comprises anexhaust pipe, a muler, and a tail pipe. The system 5 is in the form of along conduit carrying the gases from the engine at the front end of thechassis of an automobile or truck to a discharge point at the rear ofthe vehicle. The system 5 is only slightly larger than the conventionalexhaust or tail pipe (being preferably no larger than about 4 inches inmaximum diameter and preferably about 3 inches) and can be bent in anydirection at any point along its length, as well as flattened or shapedout of round, so that it can be fitted to the space available for it onthe chassis of the vehicle with which it is to be used. The system 5comprises, in downstream order, a pipe section 7, an expansion chamber11, a pipe section 53, a set of spit chambers 15, a pipe section 55, anexpansion chamber 13, a pipe section 57, and a set of spit chambers 17.The expansion chambers form high pass silencing elements and the sets ofspit chambers form low pass silencing elements. The various parts of thesystem are suitably secured together, as by spotwelds x.

The first silencing component in system 5 is the pipe section 7 thatconveys the gases away from the exhaust manifold 3. This should beformed of tubing having walls consisting of more than one layer ofmetal. We definitely prefer that the pipe 7 be laminated pipe comprisingtwo or more imperforate, single wall, seam-welded pipes, one inside theother and in loose contact with each other. The pipe section 7 will actto contain side noise in this part of the system.

The second component of the system 5 is a high pass member in the formof an expansion chamber for attenuating notes in the exhaust gases. Thesystem 5 utilizes two such members 11 and 13. It may be noted that bylaminating the outer casing of the -rst expansion chamber 11, which isclose to the exhaust manifold 3, member 11 can also act to contain orattenuate pipe noise. It is most desirable to have the laminated memberas close as possible to the exhaust manifold 3 and if for some reason itis not possible or not desirable to use the laminated section 7, thenthe expansion chamber 11 should be laminated. Also, if it is found thatlamination of the pipe section 7 is insufficient to contain side noise,the expansion chamber 11 may also be laminated as may pipe section 53.

The third component of the system 5 is a low pass member in the form ofa set of spit chambers for removing roughness or sharpness and highfrequencies not eliminated or contained by the expansion chambers or thelaminated pipe. The system 5 utilizes two sets 15 and 17 of spitchambers, each of which includes several such chambers, preferably fouror more. In a downstream direction it will be noted that the high passmember comes rst and the low pass member last and that the componentsare alternated. We prefer to have a set of spit chambers as close aspossible to the end of system.

It is possible to incorporate within an expansion charnber other meansfor making the silencing more effective. For example, in the expansionchamber 11 we have a central transverse partition 19 and this supports atube 21 as well as subdivides the casing 11 into two internalsubchambers 23 and 25. The casing of the chamber 11 may be formed withintegral reduced end sections 27 and 29 which contain and support aninlet tube 31 and an outlet tube 33. The confronting faces 35 and 37 ofthe tubes 31 and 21 may be cut off on sharp angles as shown and also maybe provided with longitudinally extending slots 39. The same is true ofconfronting faces 41 and 43 of the tube 21 and the tube 33. The angledfaces and the slots give a broad banding effect that increases the rangeof frequencies attenuated by the expansion chamber 11. In expansionchamber 13 a partition 45 subdivides the casing into two subchambersinterconnected by a restrictive downstream extending neck 47 inpartition 45, the neck 47 being preferably of substantially the samediameter as the inner diameter of pipe 7, 53, 55 and 57. The variousexpansion subchambers can be of the same or different volurnesvdepending upon the acoustic results required by the particularapplication. We prefer to use a 3 -inch outer diameter and make thelength of the expansion chamber 3 long enough to give sufficient volume,this length normally being many times the diameter of the pipe sectionsand in all cases preferably at least 12 inches.

The spit chamber sets 15 and 17 are in the form of chambered pipes andtogether contain a sufficient nurnber of chambers to eliminate roughnessand high frequency sound. There are preferably at least four chambers ineach set for optimum results. Each of the sets comprises an outer shellthat is preferably about 21A inches in diameter which is reduced, asindicated at 47, to form a series of annular chambers 49. The chambersmay be all of the same size and we have found that 3 inches is anoptimum length. The ends of the shell are reduced in diameter to engagean internal straight-through pipe, such as the pipe 51, and to litaround the connecting pipe sections 53 and 57. The internal conduit 51contains sets of louvers 59 opening into the chamber 49, such louverspreferably being of the type disclosed in U.S. Patent No. 1,949,074. Itwill be noted that in addition to being the optimum length acoustically,the 3 inch preferred length of the chambers 49 provides a structure thatmay be readily bent or flattened to suit the available space underneathan automobile or truck.

FIGURE 5 illustrates a high and medium pass silencing component in theform of a resonator chamber 61 which may be used to attenuate very lowfrequencies if they are found to be objectionable in the system 5 aspreviously described. The unit 61 would preferably be substituted forthe chamber 11 through it may be placed at another point if that will bemore effective. It comprises an inner tube 63 which is surrounded by anouter shell to form a chamber 65 around the tube. Large, non-restrictiveopenings 67 in the tube form the only inlet and outlet to the chamber 65which therefore will act as a resonator or tuning chamber to eliminatelow frequencies to which it is tuned. The size of the chamber 61 ispreferably the same as that described in connection with the expansionchambers.

The various silencing components of system 5 may be more or lessstandardized for universal usage so that exhaust systems for variousautomobile models can be made up from them by interconnecting them insuicient number, and in optimum arrangement, by means of pipe sections.

The principles of system 5 may be embodied in a dual system as shown inFIG. 6 where there is an engine 101 having two exhaust manifolds 103 andan exhaust system 105 in the form of a long tail pipe or gas passage,the latter being shown in sections which would actually be connectedtogether to form one continuous conduit. Each of the sections has anouter tube extending the full length of the section which is preferablythree inches in maximum outer diameter. Two similar conduit sections 104lead from each of the exhaust manifolds 103 and e'ach conducts the gasesalong a passage 107 into an eX- pansion chamber 109 and then into a setof four spit chambers 111. Gases leaving the two sets of spit chambers111 enter conduit portions 113 which fit into a Y coupling 115 and thusmerge the two gas paths to provide a high pass silencing effect.

It will be seen that the entire length of each of the sections 104leading to the Y joint 115 is formed from tubing which is reduced indiameter at appropriate points to form the various chambers. An innerpipe 119 is inserted at the inlet or upstream end to form the laminated1 portion 107. The outer pipe is reduced at opposite ends of theexpansion chamber 109 as seen at 121 to provide a slight restriction anda larger variation in diameter as the gases enter and leave theexpansion chamber. Inside of the spit chamber set 111 is a perforatedtube 123 which is held in place by the reduced portion 121 and turneddown portion 124 on the downstream side of the spit chamber portion.

A conduit portion 117 forms the outlet for the Y joint 115. This is theupstream end of a conduit section 125.

The conduit section 125 is connected to a conduit section 127 tocomplete the exhaust system. The sections 125 and 127 are formed in thesame way as the sections 104, that is, each comprises a length of outertubing which is reduced in diameter at appropriate spots to provide setsof spit chambers and expansion chambers similar to 111 and 109,respectively. Thus, the section 125 has a set of spit chambers 129, anexpansion chamber 131, and another set of spit chambers 133. Itterminates in a bushing section which will receive the upstream end `137of the section 127. The section 137 may be bent in a kick-up 139 and itconducts gases to an expansion chamber 141. Gases flow downstream fromchamber 141 to a set of spit chambers 143 located just ahead of end 145of the system.

The sizes and functions of the various components of system 105 arepreferably the same as described in connection with system 5.

The systems 5 and 105 may be ceramic coated. Also, some or all of thespit chambers may be filled with a sound absorptive type material (suchas steel or copper wool) that will withstand acids and temperature ofthe type disclosed, for example in U.S. Patent 2,059,487. The conduitsmay be corrugated at points of severe bending.

Various modifications may be made in the structure shownwithout'departing from the broad spirit and scope of the invention. Thesystem may be used with inboard boats as well as automobiles.

We claim:

1. A silencing system for an internal combustion engine having anexhaust manifold comprising a section of laminated pipe for connectionat one end directly to the exhaust manifold and forming means forsilencing side noises, an expansion chamber directly connected to theother end of the laminated pipe and forming means for silencing notes, aseries of spit chambers at the outlet end of the system and formingmeans for silencing roughness, and conduit means connecting said spitchambers to said expansion chamber.

2. A small diameter, long length silencing system and tailpipe for aninternal combustion engine having an eX- haust manifold comprising alaminated pipe for connection to the manifold, a series of high passsilencing members and low pass silencing member connected to andalternating with each other, the'first of said high pass silencingmembers being connected to the end of said laminated pipe, said systemterminating in a low pass silencing member.

3. A silencing system for motor vehicles such as a passenger automobilehaving a chassis and an internal combustion engine mounted at the frontend of the chassis comprising a series of tube sections and chambersconnected together to form a gas passage extending from said engine tothe rear end of said chassis, said chambers and tube sections containingsound silencing means for attenuating the noise in exhaust gas passingtherethrough, said sound silencing means including high pass chambers ofmore than about 12 inches in length and low pass chambers of about 3inches in length, said chambers being no larger than about 4 inches indiameter and said tube sections being considerably smaller than 4 inchesin diameter, the downstream order of said sound silencing meanscomprising a laminated pipe, a high pass chamber means, and a low passchamber means.

V4. A combination straight through flow exhaust gas conduit and silencerdevice to conduct gases from the exhaust manifold of an internalcombustion engine on a vehicle through a continuous straight through110W passage to a discharge point located at a remote point on thevehicle and to simultaneouly silence the exhaust gases while conductingthem to said discharge point, said device having an inlet end and anoutlet end, a series of expansion chamber members and spit chambermembers between said inlet end and said outlet end to silence the gas,said expansion chamber members and said spit chamber members beingalternated along the length of the device, gas passage sections in saiddevice interconnecting said chamber members, said lgas passage sectionsbeing smaller in diameter than said chamber members to provide a seriesof changes in diameter of the flow passage, and a laminated conduitforming element at the inlet end of the device.

5. A combination straight through flow exhaust gas conduit and silencerdevice to conduct gases from the exhaust manifold of an internalcombustion engine on a vehicle through a continuous straight throughflow passage to a discharge point located at a remote point on thevehicle and to simultaneously silence the exhaust gases while conductingthem to said discharge point, said device having an inlet end and anoutlet end, a series of expansion chamber members and spit chambermembers to silence the gas, said expansion chamber members and said spitchamber members being alternated along the length of the device, gaspassage sections in said device interconnecting said chamber members anda laminated conduit forming element at the inlet end of the device.

6. A combination straight through flow exhaust gas conduit and silencerdevice to conduct gases from the exhaust manifold of an internalcombustion engine on a vehicle through a continuous straight throughflow passage to a discharge point located at a remote point on thevehicle and to simultaneously silence the exhaust gases while conductingthem to said discharge point, said device having an inlet end and outletend, a series of expansion chamber members and spit chamber members tosilence the gas, and gas passage sections in said device interconnectingsaid chamber members, and a laminated conduit forming element at theinlet end of the device.

7. A combination straight through ow exhaust gas conduit and silencerdevice to conduct gases from the exhaust manifold of an internalcombustion engine on a vehicle through a continuous straight through owpassage to a discharge point located at a remote point on the vehicleand to simultaneously silence the exhaust gases while conducting them tosaid discharge point, said device having an inlet end and an outlet endand a series of chamber members therebetween to silence the gas, alength of integral continuous solid wall outer pipe forming the outerwall of said device, said outer pipe having varying diameters andproviding large diameter portions and small diameter portions, integralcontinuous internal pipe mounted within at least some portions of saidouter pipe and providing a straight through gas flow passage therein andextending through at least one of said large diameter portions betweenspaced small diameter portions iat each end of said one large diameterportion to provide at least one silencing chamber member defined by theinner surface of said outer pipe and the outer surface of said innerpipe, passage means extending through the wall of said inner pipe andconnecting said one silencing chamber member to said straight throughgas ow passage, and at least the inlet end of said device being formedby a section of laminated pipe.

8. An exhaust gas system comprising only long small diameter exhaust gaspipe providing a straight through gas ilow passage extendingcontinuously between a gas inlet and a gas outlet, sound attenuatingchamber means formed in said gas tlow passage by only two coaxialtelescopically mounted pipe members, said chamber sound attenuatingmeans being formed by a iirst length of integral continuous wall outerpipe forming the outer wall of said exhaust pipe, the end portions ofsaid length of outer pipe being of reduced diameter, intermediateportions of said outer pipe being of reduced diameter, the end portionsand said intermediate portions of reduced diameter having a commoninside diameter and being circumferentially continuous at the innersurface, a length of inner pipe forming a part of the gas ow passageextending the length of the pipe and having an outside diameterapproximately equal to the inside-'diameter of the end portions and saidintermediate portions of reduced diameter, the end portions and saidintermediate portions frictionally engaging the outer surface of saidinner pipe and dividing said sound attenuating chamber means into aplurality of chamber portions along the length of pipe, gas passagemeans extending through the wall of the inner pipe and connecting saidgas lloW passage to said sound attenuating chamber means, and alaminated conduit forming element at the inlet end of said exhaustsystem.

9. In a motor vehicle having an internal combustion engine emittingexhaust gases, an exhaust gas silencing system for conveying gases fromthe engine beneath the vehicle for discharge at a remote point and tosilence sound associated therewith en route to the discharge point, saidsystem being of irregular contour for positioning within the spacebeneath the vehicle it is to occupy, said system comprising at least twodifferent exhaust gas silencing units separated each from the otheralong the path of exhaust gas in the system and exhaust gas conduitsinterconnecting said units in series in said system and connecting themto the engine to receive exhaust gas, one of said silencing units havinga housing and means for silencing exhaust gases within said housing, thelast named means of said one unit comprising structure tuned toprimarily attenuate low and medium frequency sounds in the exhaustgases, the other of said units being adapted to attenuate the highfrequency sounds and roughness in the exhaust gas and consisting solelyof an outer housing, an exhaust gas inlet, an exhaust gas outlet, aninner exhaust gas flow tube for conveying gas through the housing fromsaid exhaust gas inlet to said exhaust gas outlet, said inner tubehaving a relatively large number of perforations formed therein betweenits respective ends, and wall means for dividing the volume between saidtube and said housing into a plurality of chambers, said housing beingonly slightly larger in cross-section than said tube and said chambersbeing a small volume and in acoustic communication with the gas flowingthrough said tube via the perforations in said tube for attenuating highfrequency sounds and roughness.

10. In a motor vehicle having an internal combustion engine emittingexhaust gases, an exhaust gas silencing sys-tem for conveying gases fromthe engine beneath the vehicle for discharge at a remote point and tosilence sound associated therewith en route to the discharge point, saidsystem being of irregular contour for positioning within the spacebeneath the vehicle it is to occupy, said system comprising threedifferent exhaust gas silencing units separated each from the othersalong the path of exhaust gas in the system and exhaust gas conduitsinterconnecting said units in series in said system and connecting themto the engine to receive exhaust gas, two of said silencing units havinghousings and means for silencing exhaust gases within said housings, thelast named means of said two units comprising structure tuned toprimarily attenuate low and medium frequency sounds in the exhaustgases, the third of said units being adapted to attenuate the highfrequency sounds and roughness in the exhaust gas and consisting solelyof an outer housing, an exhaust gas inlet, an exhaust gas outlet, aninner exhaust gas flow tube for conveying gas through the housing fromsaid exhaust gas inlet to said exhaust gas outlet, said inner tubehaving a relatively large number of perforations formed therein betweenits respective ends, and wall means for dividing the volume between saidtube and said housing into at least three chambers, said housing beingonly slightly larger in cross-section than said tube and said chambersbeing of small volume and in acoustic communication with the gas flowingthrough said tube via the perforations in said tube for attenuating highfrequency sounds and roughness.

(References on following page) 7 S References Cited by the ExaminerFOREIGN PATENTS UNITED STATES PATENTS 2,059,487 11/1936 Peik 181-411639940 951952 Grrggtain,

Mackenzie et al Italy. 2,770,313 11/1956 Johnson 181-36 5 2,8088 6 10/1'1 181-36 2,855,028 :l0/132g 18]. 42 STEPHEN I. TOMSKY, Plmy Exml1e-3,009,484 11/1961 Douons 181-61 X 3,104,735 9/1963 Ludlow er a1. 181-36LEO SMILOW Exammer'

1. A SILENCING SYSTEM FOR AN INTERNAL COMBUSTION ENGINE HAVING ANEXHAUST MANIFOLD COMPRISING A SECTION OF LAMINATED PIPE FOR CONNECTIONAT ONE END DIRECTLY TO THE EXHAUST MANIFOLD AND FORMING MEANS FORSILENCING SIDE NOISES, AN EXPANSION CHAMBER DIRECTLY CONNECTED TO THEOTHER END OF THE LAMINATED PIPE AND FORMING MEANS FOR SILENCING NOTES, ASERIES OF SPIT CHAMBERS AT THE OUTLET END OF THE SYSTEM AND FORMINGMEANS FOR SILENCING ROUGHNESS, AND CONDUIT MEANS CONNECTING SAID SPITCHAMBERS TO SAID EXPANSION CHAMBER.